Fluoroalkylphosphate salts, and process for the preparation of these substances

ABSTRACT

Fluoroalkylphosphate salts of Formula I, described herein, are suitable for use, alone or in mixtures with, e.g., other salts, in electrolytes, primary batteries, secondary batteries, capacitors, supercapacitors or galvanic cells.

[0001] The present invention relates to fluoroalkylphosphate salts andto a process for their preparation. The present invention furthermorerelates to mixtures which comprise the fluoroalkylphosphate saltsaccording to the invention, and to the use of these salts or thesemixtures in electrolytes, primary batteries, secondary batteries,capacitors, supercapacitors or galvanic cells.

[0002] The spread of portable electronic equipment, such as, forexample, laptop and palmtop computers, mobile telephones or videocameras, and thus also the demand for lightweight and high-performancebatteries, has increased dramatically worldwide in recent years.

[0003] In view of this suddenly increased demand for batteries and theassociated ecological problems, the development of rechargeablebatteries with a long service life is of constantly increasingimportance.

[0004] Rechargeable lithium ion batteries have been commerciallyavailable since the early nineties. Most of these batteries work withlithium hexafluorophosphate as conductive salt. However, this lithiumsalt is an extremely hydrolysis-sensitive compound with low thermalstability, and consequently the corresponding lithium batteries, owingto these properties of the salt, can only be produced by very complexand thus also very expensive processes. In addition, thehydrolysis-sensitive compound reduces the service life and theperformance of these lithium batteries and also impairs their use underextreme conditions, such as, for example, high temperatures. For thesereasons, lithium perfluoroalkylfluorophosphates, which have betterchemical and electrochemical stabilities and high discharge efficiencycompared with conventional LiPF₆, have been developed for lithiumbatteries as conductive salts in electrolytes of high-energy lithiumbatteries. The high hydrolysis stability of lithiumperfluoralkylfluorophosphates makes them interesting as powerful lithiumbatteries in electric vehicles (M. Schmidt, U. Heider, A. Kühner, R.Oesten, M. Jungnitz, N. Ignat'ev, P. Sartori. J. of Power Sources(accepted), WO 98/15562 (Merck KGaA), P 100 08 955.0 (Merck KGaA), N.Ignat'ev and P. Sartori, J. of Fluorine Chem., 101 (2000), p. 203-207).

[0005] The disadvantage of these substances lies in their high molecularweight and the resultant low content of Li⁺ cations per weight unit ofconductive salt.

SUMMARY OF THE INVENTION

[0006] An object of the present invention is therefore to provide stableconductive salts having a higher content of cations per weight unit ofconductive salt. A further object of the invention is to extend orimprove the service life and the performance of primary and secondarybatteries, capacitors, supercapacitors and/or galvanic cells.

[0007] Upon further study of the specification and appended claims,further objects and advantages of this invention will become apparent tothose skilled in the art.

[0008] These objects are achieved by the provision of novelfluoroalkylphosphate salts of the general formula (I)

(M^(a+))_(b)[(C_(n)F_(2n+1-m)H_(m))_(y)PF_(5-y)(CR₁R₂)_(x)PF_(5−y)(C_(n)F_(2n+1-m)H_(m))_(y)]⁽²⁻⁾_((a·b/2))  (I)

[0009] in which

[0010] M^(a+) is a monovalent, divalent or trivalent cation,

[0011] a=1, 2or3,

[0012] b=2 for a=1,

[0013] b=2 for a=3,

[0014] b=1 for a=2

[0015] and in each case

[0016] 1≦n≦8,

[0017] 0≦m≦2 for n=1 or 2,

[0018] 0≦m≦4 for 3≦n≦8,

[0019] 1≦x≦12,

[0020] 0≦y≦2,

[0021] where R₁ and R₂ are identical or different and are selected fromthe group consisting of fluorine, hydrogen, or alkyl, fluoroalkyl andperfluoroalkyl substituents each having 1 to 8, preferably 1 to 3 carbonatoms, and

[0022] where the substituents (C_(n)F_(2n+1-m)H_(m)) are in each caseidentical or different.

[0023] Preference is given to fluoroalkylphosphate salts of the generalformula (I) according to the invention in which the cation M^(a+) is analkali metal cation, preferably a lithium, sodium or potassium cation,particularly preferably a lithium cation, or a magnesium or aluminiumcation.

[0024] Preference is furthermore also given to fluoroalkylphosphatesalts of the general formula (I) in which the cation M^(a+) is anorganic cation, preferably a nitrosyl cation, a nitryl cation or acation of the general formula [N(R⁷)₄]⁺, [P(R⁷)₄]⁺, [P(N(R⁷)₂)₄]⁺ or[C(N(R⁷)₂)₃]⁺, where the radicals R⁷ are in each case identical ordifferent and are

[0025] H, alkyl (C₁₋₁₀) or A,

[0026] where any H atoms in the alkyl chain may be substituted byfluorine or an aromatic radical, optionally containing heteroatoms,preferably N, O and/or S, or a cycloalkyl radical, preferably having 5-6members, optionally containing heteroatoms, preferably N, O and/or S,and/or C atoms in the alkyl chain may be replaced by heteroatoms,preferably oxygen.

[0027] A is an aromatic or cycloaliphatic radical, which in each casemay optionally contain heteroatoms, preferably selected from N, O, andS. A may be any aromatic, heteroaromatic or cycloaliphatic radicalsknown to the person skilled in the art and suitable for the preparationof [N(R⁷)₄]⁺, [P(R⁷)₄]⁺, [P(N(R⁷)₂)₄]⁺ or [C(N(R⁷)₂)₃]⁺ cations.

[0028] A is preferably in each case a 5- or 6-membered aromatic radical,optionally containing nitrogen and/or sulfur and/or oxygen atoms, or acycloalkyl radical, preferably having 5 or 6 members, particularlypreferably a phenyl or pyridine radical.

[0029] In a further preferred embodiment of the present invention, thecation M^(a+) is a heteroaromatic cation selected from the groupconsisting of the heteroaromatic cations of the general formulae (II) to(IX):

[0030] The radicals R¹ to R⁶, which may in each case be identical ordifferent, are an H radical, a halogen radical, preferably a fluorineradical, or a C₁₋₈-alkyl radical, which may optionally be substituted bythe substituents F, Cl, N(C_(r)F_((2r+1-s))H_(s))₂,O(C_(r)F_((2r+1-s))H_(s)), SO₂(C_(r)F_((2r+1-s))H_(s)) orC_(r)F_((2r+1-s))H_(s), in which 1≦r≦6 and 0≦s≦13, and 2r+1-s is ≧0.

[0031] It is also possible for one or more pair of adjacent radicals R¹to R⁶ together to be a C₁₋₈-alkylene radical, which may optionally besubstituted by the substituents F, Cl, N(C_(r)F_((2r+1-s))H_(s))₂,O(C_(r)F_((2r+1-s))H_(s)), SO₂(C_(r)F_((2r+1-s))H_(s)) orC_(r)F_((2r+1-s))H_(s), in which 1≦r≦6, 0≦s≦2r+1, and 2r+1-s is ≧0.

[0032] It should be noted that the radicals R¹ to R⁶ in theheteroaromatic cations of the general formulae (II) to (IX) cannot behalogens if the radicals R¹ to R⁶ are bonded directly to nitrogen.

[0033] Preference is likewise given to fluoroalkylphosphate salts of thegeneral formula (I) in which 1≦n≦6, preferably 1≦n≦3.

[0034] Preference is also given to fluoroalkylphosphate salts of thegeneral formula (I) in which 1≦x≦8, preferably 1≦x≦4.

[0035] Particular preference is given to fluoroalkylphosphate salts ofthe general formula (I) in which m=0.

[0036] Very particular preference is given to fluoroalkylphosphate saltsof the general formula (I) in which y=2.

[0037] Very particular preference is also given to thefluoroalkylphosphate salts of the general formula (I) according to theinvention in which R₁ and R₂ are fluorine.

[0038] Particular preference is given to the fluoroalkylphosphate saltsof the general formula (I):

(Li⁺)₂[(C₂F₅)₂PF₃(CF₂)₂PF₃(C₂F₅)₂]⁽²⁻⁾

and

(N(C₂H₅)₄ ⁺)₂[(C₂F₅)₂PF₃(CF₂)₂PF₃(C₂F₅)₂]⁽²⁻⁾

[0039] The salts of the general formula (I) according to the inventioncan be employed, both in pure form and in the form of their mixtures, asconductive salts in electrolytes, primary and secondary batteries,capacitors, super-capacitors and/or galvanic cells. The salts accordingto the invention are preferably used in pure form as conductive saltssince in this way particularly good reproducibility of theelectrochemical properties can be ensured. However, it is likewisepossible to use the salts according to the invention as conductive saltsin the form of a mixture with further salts known to the person skilledin the art.

[0040] They can be used in proportions of between 1 and 99% incombination with other conductive salts used in electrochemical cells.Suitable are, for example, conductive salts selected from the groupconsisting of LiPF₆, LiBF₄, LiCIO₄, LiAsF₆, LiCF₃SO₃, LiN(CF₃SO₂)₂,LiN(CF₃CF₂SO₂)₂, LiC(CF₃SO₂)₃ or lithium fluoroalkylphosphates of thegeneral formula Li[PF_((6−C))(C_(d)F_(2d+1))], where 1≦c≦5 and 1≦d≦8,and LiN[SO₂(C_(e)F_(2e+1))]₂, LiCSO₂(C_(e)F2_(e+1))]₃ andLi[SO₃(C_(e)F_(2e+1))], where 2≦e≦8, and mixtures thereof. The salts ofthe formula (I) and mixtures thereof can likewise be used inelectrolytes for electrochemical cells.

[0041] The electrolytes may also comprise organic isocyanates (DE 199 44603, this citation being incorporated herein by way of reference andthus being regarded as part of the disclosure) in order to reduce thewater content.

[0042] The invention furthermore relates to a process for thepreparation of fluoro-alkylphosphate salts according to the invention.In this process, at least onefluoro-α,ω-bis[(fluoroalkyl)fluorophosphorano)alkane is reacted with atleast one fluoride salt of the general formula (X)

(M^(a+))[F⁻]_(a)  (X)

[0043] in which (M^(a+)) and a are as defined above, in solution to givea fluoroalkyl-phosphate salt of the general formula (I) according to theinvention, and the latter is, where appropriate, purified and/orisolated by conventional methods.

[0044] In a preferred embodiment of the process according to theinvention, the fluoro-α,ω-bis[(fluoroalkyl)fluorophosphorano]alkanesemployed are at least one compound of the general formula (XI)

(C_(n)F_(2n+1-m)H_(m))_(y)PF_(4-y)(CR₁R₂)_(x)PF_(4-y)(C_(n)F_(2n+1-m)H_(m))_(y)  (XI)

[0045] in which

[0046] 1≦n≦8, 0≦m≦2 for n=1 or 2, 0≦m≦4 for 3≦n≦8, 1≦x≦12, 0≦y≦2,

[0047] where R₁ and R₂ are identical or different and are selected fromthe group consisting of fluorine, hydrogen, or alkyl, fluoroalkyl andperfluoroalkyl substituents each having 1 to 8, preferably 1 to 3 carbonatoms, and where the substituents (C_(n)F_(2n+1-m)H_(m)) are in eachcase identical or different.

[0048] Of the processes according to the invention, preference is givento those in which the compound of the general formula (X) is employed inan excess of up to 10 fold, preferably up to 5 fold, particularlypreferably up to 2 fold, based on the amount offluoro-α,ωbis[(fluoroalkyl)fluorophosphorano]alkane(s). Compounds of thegeneral formula (X) are very particularly preferably employed in twicethe equimolar amount based on thefluoro-α,ω-bis[(fluoro-alkyl)fluorophosphorano]alkane employed.

[0049] In the processes according to the invention, the reaction withthe fluoride salt of the general formula (X) is preferably carried outat a temperature of from −35 to +80° C., preferably from −20 to +50° C.,particularly from 10 to 25° C.

[0050] Suitable solvents for the above-mentioned processes are organiccarbonates, preferably ethylene carbonate, propylene carbonate, butylenecarbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonateor methyl propyl carbonate, organic esters, preferably methyl formate,ethyl formate, methyl acetate, ethyl acetate, methyl propionate, ethylpropionate, methyl butyrate, ethyl butyrate or γ-butyrolactone, organicethers, preferably diethyl ether, dimethoxyethane or diethoxyethane,organic amides, preferably dimethyl-formamide or dimethylacetamide,sulfur-containing solvents, preferably dimethyl sulfoxide, dimethylsulfide, diethyl sulfide or propane sulfone, aprotic solvents,preferably acetonitrile, acrylonitrile, propionitrile or acetone, or atleast partially fluorinated derivatives of the above-mentioned solvents,or mixtures of at least two of these solvents and/or fluorinatedderivatives of these solvents.

[0051] The fluoroalkylphosphate salts of the general formula (I)according to the invention are also suitable for use in solidelectrolytes. For the purposes of the present invention, the term solidelectrolytes is taken to mean both polymer electrolytes, which usuallycomprise an optionally crosslinked polymer and a conductive salt, andalso gel electrolytes, which, besides an optionally cross-linked polymerand a conductive salt, usually additionally comprise at least onesolvent.

[0052] The present invention therefore furthermore relates to a mixturecomprising

[0053] a) at least one fluoroalkylphosphate salt of the general formula(I) and

[0054] b) at least one polymer.

[0055] For the purposes of the present invention, the term mixturecovers pure mixtures of components a) and b), mixtures in which the saltof component a) is included in the polymer of component b), and mixturesin which chemical and/or physical bonds exist between the salt ofcomponent a) and the polymer of component b).

[0056] In a preferred embodiment of the present invention, the mixtureaccording to the invention comprises from 5 to 90% by weight ofcomponent a) and from 95 to 5% by weight of component b), particularlypreferably from 10 to 80% by weight of component a) and from 90 to 20%by weight of component b). The stated weight ratios are in each casebased on the sum of components a) and b).

[0057] As component b), the mixture according to the inventionpreferably comprises a homopolymer or copolymer of acrylonitrile,vinylidene difluoride, methyl (meth)acrylate, tetrahydrofuran, ethyleneoxide, siloxane, phosphazene or a mixture of at least two of theabove-mentioned homopolymers and/or copolymers.

[0058] Component b) is particularly preferably a homopolymer orcopolymer of vinylidene difluoride, acrylonitrile, methyl (meth)acrylateor tetrahydrofuran, very particularly preferably a homopolymer orcopolymer of vinylidene difluoride.

[0059] These homopolymers and copolymers of vinylidene fluoride aremarketed under the name Kynare® and Kynarflex® by Atofina Chemicals,Inc., and under the name Solef® by Solvay.

[0060] The polymers used in accordance with the invention may also be atleast partially crosslinked. The crosslinking can be carried out usingknown crosslinking agents by conventional methods known to the personskilled in the art.

[0061] Besides the fluoroalkylphosphate salts of the general formula (I)and the polymers, the mixture according to the invention mayadditionally comprise a solvent or a solvent mixture of two or moresolvents.

[0062] Preferred solvents are organic carbonates, preferably ethylenecarbonate, propylene carbonate, butylene carbonate, dimethyl carbonate,diethyl carbonate, ethyl methyl carbonate or methyl propyl carbonate,organic esters, preferably methyl formate, ethyl formate, methylacetate, ethyl acetate, methyl propionate, ethyl propionate, methylbutyrate, ethyl butyrate or y-butyrolactone, organic ethers, preferablydiethyl ether, dimethoxyethane or diethoxyethane, organic amides,preferably dimethylformamide or dimethylacetamide, sulfur-containingsolvents, preferably dimethyl sulfoxide, dimethyl sulfide, diethylsulfide or propane sulfone, aprotic solvents, preferably acetonitrile,acrylonitrile or acetone, or at least partially fluorinated derivativesof the above-mentioned solvents, or mixtures of at least two of thesesolvents and/or fluorinated derivatives of these solvents.

[0063] The present invention furthermore relates to the use of at leastone fluoroalkyl-phosphate salt according to the invention or of amixture according to the invention in electrolytes, primary batteries,secondary batteries, capacitors, supercapacitors and/or galvanic cells,if desired also in combination with further, known conductive saltsand/or additives.

[0064] The invention furthermore relates to electrolytes, primary andsecondary batteries, capacitors, supercapacitors and galvanic cellswhich contain at least one fluoroalkylphosphate salt of the generalformula (I) according to the invention or a mixture according to theinvention and, if desired, further conductive salts and/or additives.Further conductive salts and additives are known to the person skilledin the art, for example from Doron Auerbach, NonaqueousElectrochemistry, Marc Dekker Inc., New York 1999; D.Linden, Handbook ofBatteries, Second Edition, McGraw-Hill Inc., New York 1995, and G.Mamantov and A. I. Popov, Chemistry of Nonaqueous Solutions, CurrentProgress, VCH Verlagsgeselischaft, Weinheim 1994. They are herebyincorporated by way of reference and are regarded as part of thedisclosure.

[0065] Electrolytes according to the invention preferably have aconcentration of the fluoroalkylphosphate salt(s) according to theinvention of from 0.01 to 3 mol/l, preferably from 0.01 to 2 mol/l,particularly preferably from 0.1 to 1.5 mol/l.

[0066] As solvents for the salts according to the invention, theelectrolytes preferably comprise organic carbonates, preferably ethylenecarbonate, propylene carbonate, butylene carbonate, dimethyl carbonate,diethyl carbonate, ethyl methyl carbonate or methyl propyl carbonate,organic esters, preferably methyl formate, ethyl formate, methylacetate, ethyl acetate, methyl propionate, ethyl propionate, methylbutyrate, ethyl butyrate or y-butyrolactone, organic ethers, preferablydiethyl ether, dimethoxyethane or diethoxyethane, organic amides,preferably dimethylformamide or dimethylacetamide, sulfur-containingsolvents, preferably dimethyl sulfoxide, dimethyl sulfide, diethylsulfide or propane sulfone, aprotic solvents, preferably acetonitrile,acrylonitrile or acetone, or at least partially fluorinated derivativesof the above-mentioned solvents, or mixtures of at least two of thesesolvents and/or fluorinated derivatives of these solvents.

[0067] The fluoroalkylphosphate salts according to the invention and themixtures according to the invention have the advantage that they exhibitabsolutely no or virtually no signs of decomposition over a very longperiod in the presence of water and have good to very good solubility inmost solvents or solvent mixtures.

[0068] Furthermore, they have high thermal stability and high chemicalstability both in the solid state and in the dissolved state. Thus, thesalts and mixtures according to the invention are stable, for example tostrong oxidants, such as, for example, to highly oxidising electrodematerials, such as, for example, LiMn₂O₄, LiNiO₂ or LiCoO₂.

[0069] These properties enable electrolytes, batteries, capacitors,supercapacitors and galvanic cells which contain these conductive saltsto be employed under extreme conditions, such as, for example, at hightemperatures, without their service life and performance being impairedby these conditions.

[0070] Furthermore, the corresponding batteries, capacitors,supercapacitors and galvanic cells are distinguished by very goodvoltage constancy, unrestricted ability to function over many chargingand discharging cycles, and by low production costs.

[0071] The use of the fluoroalkylphosphate salts according to theinvention or the mixtures according to the invention in large batteries,as used, for example, in electric road vehicles or hybrid road vehicles,is likewise very advantageous since, in the case of damage to thebatteries, such as, for example, in the case of an accident, includingin the case of contact with water, for example through atmosphericmoisture or extinguishing water, toxic and highly caustic hydrogenfluoride is not formed.

[0072] The compounds according to the invention and mixtures thereof canbe used in electrolytes for electrochemical cells. They can be employedas conductive salts or additives. They can likewise be used inproportions of between 1 and 99% in combination with other conductivesalts used in electrochemical cells. Suitable are, for example,conductive salts selected from the group consisting of LiPF₆, LiBF₄,LiCIO₄, LiAsF₆, LiCF₃SO₃, LiN(CF₃SO₂)₂, LiN(CF₃CF₂SO₂)₂ and LiC(CF₃SO₂)₃and mixtures thereof.

[0073] The electrolytes may also comprise organic isocyanates (DE 199 44603) for reducing the water content.

[0074] It is also possible for compounds of the general formula

[([R¹(CR²R³)_(k)]_(l)A_(x))_(y)Kt]⁺ ⁻N(CF₃)₂

[0075] where

[0076] Kt is N, P, As, Sb, S or Se

[0077] A is N, P, P(O), O, S, S(O), SO₂, As, As(O), Sb or Sb(O)

[0078] R¹, R² and R³

[0079] are identical or different

[0080] and are H, halogen, substituted and/or unsubstituted alkylC_(n)H_(2n+1), substituted and/or unsubstituted alkenyl having 2-18carbon atoms and one or more double bonds, substituted and/orunsubstituted alkynyl having 2-18 carbon atoms and one or more triplebonds, substituted and/or unsubstituted cycloalkyl C_(m)H_(2m−1), mono-or polysubstituted and/or unsubstituted phenyl, or substituted and/orunsubstituted heteroaryl,

[0081] A may be included in R¹, R² and/or R³ in various positions,

[0082] Kt may be included in a cyclic or heterocyclic ring,

[0083] the groups bonded to Kt may be identical or different,

[0084] where

[0085] n is 1-18

[0086] m is 3-7

[0087] k is 0 or 1-6

[0088] l is 1 or 2 in the case where x=1 and 1 in the case where x=0

[0089] x is 0 or 1

[0090] y is 1-4

[0091] to be present (DE 19941566 and U.S. Ser. No. 09/654,519, filedSep. 1, 2000). The process for the preparation of the compounds ischaracterised in that an alkali metal salt of the general formula

D⁺ ⁻N(CF₃)₂

[0092] where D⁺ is selected from the group consisting of the alkalimetals, is reacted, in a polar organic solvent, with a salt of thegeneral formula

[([R¹(CR²R³)_(k)]_(l)A_(x))_(y)Kt]⁺ ⁻E

[0093] where

[0094] Kt, A, R¹, R², R³, k, l, x and y are as defined above, and ⁻E isF⁻, Cl⁻, Br⁻, I⁻, BF₄ ⁻, ClO₄ ⁻, AsF₆ ⁻, SbF₆ ⁻ or PF₆ ⁻.

[0095] The compounds according to the invention may also be present inelectrolytes comprising compounds of the formula

X—(CYZ)_(m)—SO₂N(CR¹R²R³)₂

[0096] where

[0097] X is H, F, Cl, C_(n)F_(2n+1), C_(n)F_(2n−1) or(SO₂)_(k)N(CR¹R²R³)₂

[0098] Y is H, F or Cl

[0099] Z is H, F or Cl

[0100] R¹, R² and R³ are H and/or alkyl, fluoroalkyl or cycloalkyl

[0101] m is 0-9 and, if X=H, m≠0

[0102] n is 1-9

[0103] k is 0 if m=0 and k=1 if m=1-9,

[0104] prepared by reacting partially or perfluorinated alkylsulfonylfluorides with dimethylamine in organic solvents (DE 199 466 73 and U.S.Ser. No. 09/671,619, filed Sep. 28, 2000).

[0105] It is also possible to use electrolytes comprising complex saltsof the general formula (DE 199 51 804 and U.S. Ser. No. 09/698,478,filed Oct. 30, 2000)

M^(x+)[EZ]_(x/y) ^(y−)

[0106] in which:

[0107] x and y are 1, 2, 3,4, 5 or 6

[0108] M^(x+) is a metal ion

[0109] E is a Lewis acid selected from the group consisting of

[0110] BR¹R²R³, AlR¹R²R³, PR¹R²R³R⁴R⁵, AsR¹R²R³R⁴R⁵ and VR¹R²R³R⁴R⁵,

[0111] R¹ to R⁵ are identical or different, are optionally bondeddirectly to one another by a single or double bond, and each,individually or together, are

[0112] a halogen (F, Cl or Br),

[0113] an alkyl or alkoxy radical (C₁ to C₈), which may be partially orfully substituted by F, Cl or Br,

[0114] an aromatic ring, optionally bonded via oxygen, from the groupconsisting of phenyl, naphthyl, anthracenyl and phenanthrenyl, which maybe unsubstituted or mono- to hexasubstituted by alkyl (C₁ to C₈) or F,Cl or Br,

[0115] an aromatic heterocyclic ring, optionally bonded via oxygen, fromthe group consisting of pyridyl, pyrazyl and pyrimidyl, which may beunsubstituted or

[0116] mono- to tetrasubstituted by alkyl (C₁ to C₈) or F, Cl or Br, and

[0117] Z is OR⁶, NR⁶R⁷, CR⁶R⁷R⁸, OSO₂R⁶, N(SO₂R⁶)(SO₂R⁷),C(SO₂R⁶)(SO₂R⁷)(SO₂R⁸) or OCOR⁶, where

[0118] R⁶ to R⁸ are identical or different, are optionally bondeddirectly to one another by a single or double bond and are each,individually or together,

[0119] hydrogen or as defined for R¹ to R⁵.

[0120] These complex salts can be prepared by reacting a correspondingboron or phosphorus Lewis acid/solvent adduct with a lithium ortetraalkylammonium imide, methanide or triflate.

[0121] Borate salts (DE 199 59 722 and U.S. Ser. No. 09/732,899, filedDec. 11, 2000) of the general formulae

[0122] in which:

[0123] M is a metal ion or tetraalkylammonium ion,

[0124] x and y are 1, 2, 3, 4, 5 or 6,

[0125] R¹ to R⁴ are identical or different and are alkoxy or carboxylradicals (C₁-C₈), which are optionally bonded directly to one another bya single or double bond, may also be present. These borate salts areprepared by reacting lithium tetraalkoxyborate or a 1:1 mixture oflithium alkoxide with a borate with a suitable hydroxyl or carboxylcompound in a ratio of 2:1 or 4:1 in an aprotic solvent.

[0126] Additives, such as silane compounds of the general formula

SiR¹R²R³R⁴

[0127] where R¹ to R⁴ are H

[0128] C_(y)F_(2y+1-z)H_(z)

[0129] OC_(y)F_(2y+1-z)H_(z)

[0130] OC(O)C_(y)F_(2y+1-z)H_(z)

[0131] OSO₂C_(y)F_(2y+1-z)H_(z)

[0132] and

[0133] 1≦x≦6

[0134] 1≦y≦8 and

[0135] 0≦z≦2y+1

[0136] and

[0137] R¹-R⁴ are identical or different

[0138] and are an aromatic ring from the group consisting of phenyl andnaphthyl, which may be unsubstituted or monosubstituted orpolysubstituted by F, C_(y)F_(2y+1-z)H_(z), OC_(y)F_(2y+1-z)H_(z),OC(O)C_(y)F_(2y+1-z)H_(z), OSO₂C_(y)F_(2y+1-z)H_(z) orN(C_(n)F_(2n+1-z)H_(z))₂, or are a heterocyclic aromatic ring from thegroup consisting of pyridyl, pyrazyl and pyrimidyl, each of which may bemonosubstituted or polysubstituted by F, C_(y)F_(2y+1-z)H_(z),OC_(y)F_(2y+1-z)H_(z), OC(O)C_(y)F_(2y+1-z)H_(z),OSO₂C_(y)F_(2y+1-z)H_(z) or N(C_(n)F_(2n+1-z)H_(z))₂ (DE 100 276 26 andU.S. Ser. No. 09/875,047, filed Jun. 17, 2001), may also be present.

[0139] The compounds according to the invention may also be employed inelectrolytes comprising lithium fluoroalkylphosphates of the followingformula

Li⁺[PF_(x)(C_(y)F_(2y+1-z)H_(z))_(6−x)]⁻

[0140] in which

[0141] 1≦x≦5

[0142] 3≦y≦8

[0143] 0≦z≦2y+1

[0144] and the ligands (C_(y)F_(2y+1-z)H_(z)) may be identical ordifferent, with the exception of the compounds of the general formula

Li⁺[PF_(a)(CH_(b)F_(c)(CF₃)_(d))_(e)]⁻

[0145] in which a is an integer from 2 to 5, b=0 or 1, c=0 or 1, d=2 ande is an integer from 1 to 4, with the provisos that b and c are notsimultaneously each=0, and the sum a+e is equal to 6, and the ligands(CH_(b)F_(c)(CF₃)_(d)) may be identical or different (DE 100 089 55 andU.S. Ser. No. 09/572,939, filed May 18, 2000). The process for thepreparation of these lithium fluoroalkylphosphates is characterised inthat at least one compound of the general formula

H_(m)P(C_(n)H_(2n+1))_(3−m)  (III),

OP(C_(n)H_(2n+1))₃  (IV),

Cl_(m)P(C_(n)H_(2n+1))_(3−m)  (V),

F_(m)P(C_(n)H_(2n+1))_(3−m)  (VI),

Cl_(o)P(C_(n)H_(2n+1))_(5−o)  (VII),

F_(o)P(C_(n)H_(2n+1))_(5−o)  (VII),

[0146]  in each of which

[0147] 0≦m≦2, 3≦n≦8 and 0≦o≦4,

[0148] is fluorinated by electrolysis in hydrogen fluoride, theresultant mixture of fluorination products is separated by extraction,phase separation and/or distillation, the resultant fluorinatedalkylphosphorane is reacted with lithium fluoride in an aprotic solventmixture with exclusion of moisture, and the resultant salt is purifiedand isolated by conventional methods. The compounds according to theinvention may also be employed in electrolytes which comprise salts ofthe formula

Li[P(OR¹)_(a)(OR²)_(b)(OR³)_(c)(OR⁴)_(d)F_(e)]

[0149] in which 0<a+b+c+d≦5 and a+b+c+d+e=6, and R¹ to R⁴, independentlyof one another, are alkyl, aryl or heteroaryl radicals, where at leasttwo of R¹ to R⁴ may be linked directly to one another via a single ordouble bond (DE 100 16 801 and U.S. Ser. No. 091825,868, filed Apr. 15,2001). The compounds are prepared by reacting phosphorus(V) compounds ofthe general formula

P(OR¹)_(a)(OR²)_(b)(OR³)_(c)(OR⁴)_(d)F_(e)

[0150] in which 0<a+b+c+d≦5 and a+b+c+d+e=5, and R¹ to R⁴ are as definedabove, with lithium fluoride in the presence of an organic solvent. Itis also possible for ionic liquids of the general formula

K⁺A⁻

[0151] in which:

[0152] K⁺ is a cation selected from the group consisting of

[0153]  where R¹ to R⁵ are identical or different, are optionally bondeddirectly to one another by a single or double bond, and each,individually or together, have the following meaning:

[0154] H,

[0155] halogen,

[0156] an alkyl radical (C₁ to C₈), which may be partially or fullysubstituted by further groups, F, Cl, N(C_(n)F_((2n+1-x))H_(x))₂,O(C_(n)F_((2n+1-x))H_(x)), SO₂(C_(n)F_((2n+1-x))H_(x)) orC_(n)F_((2n+1-x))H_(x), where 1<n<6 and 0<x≦13, and

[0157] A⁻ is an anion selected from the group consisting of

[0158] [B(OR¹)_(n)(OR²)_(m)(OR³)_(o)(OR⁴)_(p)]⁻

[0159] where 0≦n, m, o, p≦4, and

[0160] m+n+o+p=4,

[0161] where R¹ to R⁴ are different or are identical in pairs, areoptionally bonded directly to one another by a single or double bond andare each, individually or together, an aromatic ring from the groupconsisting of phenyl, naphthyl, anthracenyl and phenanthrenyl, which maybe unsubstituted or monosubstituted or polysubstituted byCnF_((2n+1-x))H_(x), where 1<n<6 and 0<x≦13, or halogen (F, Cl or Br),

[0162] an aromatic heterocyclic ring from the group consisting ofpyridyl, pyrazyl and pyrimidyl, which may be unsubstituted ormonosubstituted or polysubstituted by C_(n)F_((2n+1-x))H_(x), where1<n<6 and 0<x≦13, or halogen (F, Cl or Br), an alkyl radical (C₁ to C₈),which may be partially or fully substituted by further groups,preferably F, Cl, N(C_(n)F_((2n+1-x))H_(x))₂, O(C_(n)F_((2n+1-x))H_(x)),SO₂(C_(n)F_((2n+1-x))H_(x)) or C_(n)F_((2n+1-x))H_(x), where 1<n<6 and0<x≦13,

[0163] or OR¹ to OR⁴

[0164] individually or together are an aromatic or aliphatic carboxyl,dicarboxyl, oxysulfonyl or oxycarbonyl radical, which may be partiallyor fully substituted by further groups, preferably F, Cl,N(C_(n)F_((2n+1-x))H_(x))₂, O(C_(n)F_((2n+1-x))H_(x)),SO₂(C_(n)F_((2n+1-x))H_(x)) or C_(n)F_((2n+1-x))H_(x), where 1<n<6 and0<x≦13 (DE 100 265 65 and U.S. Ser. No. 09/866,926 filed May 30, 2001),to be present in the electrolyte.

[0165] It is also possible for ionic liquids K⁺k⁻ where K⁺ is as definedabove and A⁻ is an anion selected from the group consisting of

[PF_(x)(C_(y)F_(2y+1-z)H_(z))_(6−x)]⁻

[0166] and

[0167] 1≦x<6

[0168] 1≦y≦8 and

[0169] 0≦z≦2y+1

[0170] to be present (DE 100 279 95 and U.S. Ser. No. 09/877,259, filedJun. 11, 2001).

[0171] The compounds according to the invention may also be present inelectrolytes comprising compounds of the following formula:

NR¹R²R³

[0172] in which

[0173] R¹ and R² are H, C_(y)F_(2y+1-z)H_(z) or (C_(n)F_(2n−m)H_(m))X,where X is an aromatic or heterocyclic radical, and

[0174] R³ is (C_(n)F_(2n−m)H_(m))Y, where Y is a heterocyclic radical,or

[0175] (C_(o)F_(2o−p)H_(p))Z, where Z is an aromatic radical,

[0176] and where n, m, o, p, y and z satisfy the following conditions:

[0177] 0≦n≦6,

[0178] 0≦m≦2n,

[0179] 2≦o≦6,

[0180] 0≦p≦2o,

[0181] 1≦y≦8, and

[0182] 0≦z≦2y+1,

[0183] for reducing the acid content in aprotic electrolyte systems inelectrochemical cells.

[0184] It is also possible for fluoroalkylphosphates of the generalformula

M^(n+)[PF_(x)(C_(y)F_(2y+1-z)H_(z))_(6−x)]_(n) ⁻

[0185] in which

[0186] 1≦x≦6

[0187] 1≦y≦8

[0188] 0≦z≦2y+1

[0189] 1≦n≦3 and

[0190] M^(n+) is a monovalent to trivalent cation, in particular:

[0191] NR¹R²R³R⁴,

[0192] PR¹R²R³R⁴,

[0193] P[(NR¹R²)_(k)R³ _(m)R⁴ _(4−k−m)] (where k=1-4, m=0-3 and k+m≦4),

[0194] C(NR¹R²)(NR³R⁴)(NR⁵R⁶)

[0195] C(aryl)₃, Rb or tropylium,

[0196] where R¹ to R⁸ are H, alkyl or aryl (C₁-C₈), which may bepartially substituted by F, Cl or Br,

[0197] with the exception of M^(n+)=Li⁺, Na⁺, Cs⁺, K⁺ and Ag⁺. Thesefluoroalkyl-phosphates are obtainable by reacting phosphoranes with afluoride or metal fluoroalkylphosphates with a fluoride or chloride inorganic aprotic solvents (DE 100 388 58 and U.S. Ser. No. 09/918,464,filed August, 2001).

[0198] The electrolyte may also comprise a mixture that comprises

[0199] a) at least one lithium fluoroalkylphosphate salt of the generalformula

Li⁺[PF_(x)(C_(y)F_(2y+1-z)H_(z))_(6−x)]⁻

[0200]  in which

[0201] 1≦x≦5

[0202] 1≦y≦8, and

[0203] 0≦z≦2y+1

[0204] and the ligands (C_(y)F_(2y+1-z)H_(z)) are in each case identicalor different, and

[0205] b) at least one polymer (DE 100 58 264).

[0206] The electrolyte may also comprise tetrakisfluoroalkyl boratesalts of the general formula

M^(n+)([BR₄]⁻)_(n)

[0207] in which

[0208] M^(n+) is a monovalent, divalent or trivalent cation,

[0209] the ligands R are in each case identical and are (C_(x)F_(2x+1)),where 1≦x≦8, and n=1, 2 or 3 (DE 100 558 11). The process for thepreparation of tetrakisfluoroalkyl borate salts is characterised in thatat least one compound of the general formula M^(n+) ([B(CN)₄]⁻)_(n), inwhich M^(n+) and n are as defined above, is fluorinated by reaction withat least one fluorinating agent in at least one solvent, and theresultant fluorinated compound is purified and isolated by conventionalmethods.

[0210] The electrolyte may also comprise borate salts of the generalformula

M^(n+)[BF_(x)(C_(y)F_(2y+1-z)H_(z))_(4−x)]_(n) ⁻

[0211] in which:

[0212] 1<x<3, 1≦y≦8 and 0≦z≦2y+1, and

[0213] M is a monovalent to trivalent cation (1≦n≦3), apart frompotassium and barium,

[0214] in particular:

[0215] Li,

[0216] NR¹R²R³R⁴, PR⁵R⁶R⁷R⁸, P(NR⁵R⁶)_(k)R⁷ _(m)R⁸ _(4−k−m) (wherek=1-4, m=0-3 and k+m≦4), or

[0217] C(NR⁵R⁶)(NR⁷R⁸)(NR⁹R¹⁰), where

[0218] R¹ to R⁴ are C_(y)F_(2y+1-z)H_(z) and

[0219] R⁵ to R¹⁰ are H or C_(y)F_(2y+1-z)H_(z), or

[0220] an aromatic heterocyclic cation, in particular a nitrogen- and/oroxygen- and/or sulfur-containing aromatic heterocyclic cation (DE 101031 89 and U.S. Ser. No. 10/050,151, filed Jan. 18, 2002). The processfor the preparation of these compounds is characterised in that

[0221] a) BF₃/solvent complexes are reacted 1:1 with alkyllithium withcooling, the majority of the solvent is removed after slow warming, andthe solid is subsequently filtered off and washed with a suitablesolvent, or

[0222] b) lithium salts in a suitable solvent are reacted 1:1 withB(CF₃)F₃ salts, the mixture is stirred at elevated temperature, thesolvent is removed, aprotic non-aqueous solvents, preferably solventswhich are used in electrochemical cells, are added to the reactionmixture, and the mixture is dried, or

[0223] c) B(CF₃)F₃ salts are reacted 1:1 to 1:1.5 with lithium salts inwater at elevated temperature and heated at the boiling point for from0.5 to 2 hours, the water is removed, aprotic non-aqueous solvents,preferably solvents which are used in electrochemical cells, are addedto the reaction mixture and the mixture is dried.

[0224] The electrolyte may also comprise fluoroalkylphosphate salts ofthe general formula

M^(n+)([PF_(x)(C_(y)F_(2y+1-z)H_(z))_(6−x)]⁻)_(n)

[0225] in which

[0226] M^(n+) is a monovalent, divalent or trivalent cation,

[0227] 1≦x≦5,

[0228] 1≦y≦8 and

[0229] 0≦z≦2y+1, n=1, 2 or 3, and the ligands (C_(y)F_(2y+1-z)H_(z)) arein each case identical or different, where the fluoroalkylphosphatesalts in which M^(n+) is a lithium cation and the salts

[0230] M⁺([PF₄(CF₃)₂]⁻) where M⁺=Cs⁺, Ag⁺ or K⁺,

[0231] M⁺([PF₄(C₂F₅)₂]⁻) where M⁺=Cs⁺,

[0232] M⁺([PF₃(C₂F₅)₃]⁻) where M⁺=Cs⁺, K⁺, Na⁺ or para-Cl(C₆H₄)N₂ ⁺,

[0233] M⁺([PF₃(C₃F₇)₃]⁻) where M⁺=Cs⁺, K⁺, Na⁺, para-Cl(C₆H₄)N₂ ⁺ or

[0234] para-O₂N(C₆H₄)N₂ ⁺, are excluded (DE 100 558 12). The process forthe preparation of these fluoroalkylphosphate salts is characterised inthat at least one compound of the general formula

H_(r)P(C_(s)H_(2s+1))_(3−r),

OP(C_(s)H_(2s+1))₃,

Cl_(r)P(C_(s)H_(2s+1))_(3−r),

F_(r)P(C_(s)H_(2s+1))_(3−r),

Cl_(t)P(C_(s)H_(2s+1))_(5−t) and/or

F_(t)P(C_(s)H_(2s+1))_(5−t),

[0235]  in which in each case

[0236] 0≦r≦2

[0237] 3≦s≦8 and

[0238] 0≦t≦4,

[0239] is fluorinated by electrolysis in hydrogen fluoride, theresultant mixture of fluorination products is separated, and theresultant fluorinated alkylphosphorane is reacted with a compound of thegeneral formula M^(n+)(F⁻)_(n), in which M^(n+) and n are as definedabove, in an aprotic solvent or solvent mixture with exclusion ofmoisture, and the resultant fluoroalkylphosphate salt is purified andisolated by conventional methods.

[0240] The compounds according to the invention can be used inelectrolytes for electrochemical cells containing positive-electrodematerial consisting of coated metal cores selected from the groupconsisting of Sb, Bi, Cd, In, Pb, Ga and tin or alloys thereof (DE 10016 024 and U.S. Ser. No. 09/821,683, filed Mar. 30, 2001). The processfor the preparation of this positive-electrode material is characterisedin that

[0241] a) a suspension or sol of the metal or alloy core in urotropin isprepared,

[0242] b) the suspension is emulsified with C₅-C₁₂-hydrocarbons,

[0243] c) the emulsion is precipitated onto the metal or alloy cores,and

[0244] d) the metal hydroxides or oxyhydroxides are converted into thecorresponding oxide by heating the system.

[0245] The compounds according to the invention can also be employed inelectrolytes for electrochemical cells having negative electrodes madefrom common lithium intercalation and insertion compounds, but also withnegative-electrode materials consisting of lithium mixed oxide particlescoated with one or more metal oxides (DE 199 22 522 and U.S. Ser. No.09/959,983, filed Nov. 14, 2001). They may also consist of lithium mixedoxide particles which are coated with one or more polymers (DE 199 46066 and U.S. Ser. No. 09/668,282, filed Sep. 25, 2000), obtained by aprocess in which the particles are suspended in a solvent, and thecoated particles are subsequently filtered off, dried and optionallycalcined. The compounds according to the invention may likewise beemployed in systems having negative electrodes consisting of lithiummixed oxide particles with one or more coatings of alkali metalcompounds and metal oxides (DE100 14 884 and U.S. Ser. No. 09/816,663,filed Mar. 26, 2001). The process for the production of these materialsis characterised in that the particles are suspended in an organicsolvent, an alkali metal salt compound suspended in an organic solventis added, metal oxides dissolved in an organic solvent are added, ahydrolysis solution is added to the suspension, and the coated particlesare subsequently filtered off, dried and calcined. The compoundsaccording to the invention can likewise be employed in systemscomprising positive-electrode materials with doped tin oxide (DE 100 25761 and U.S. Ser. No. 09/864,874, filed Mar. 25, 2001). Thispositive-electrode material is prepared by

[0246] a) adding urea to a tin chloride solution,

[0247] b) adding urotropin and a suitable doping compound to thesolution,

[0248] c) emulsifying the resultant sol in petroleum ether,

[0249] d) washing the resultant gel and removing the solvent by suction,and

[0250] e) drying and heating the gel.

[0251] The compounds according to the invention can likewise be employedin systems comprising positive-electrode materials with reduced tinoxide (DE 100 257 62 and U.S. Ser. No. 09/864,092, filed May 24, 2001).This positive-electrode material is prepared by

[0252] a) adding urea to a tin chloride solution,

[0253] b) adding urotropin to the solution,

[0254] c) emulsifying the resultant sol in petroleum ether,

[0255] d) washing the resultant gel and removing the solvent by suction,

[0256] e) drying and heating the gel, and

[0257] f) exposing the resultant SnO₂ to a reducing gas stream in anaeratable oven.

BRIEF DESCRIPTION OF THE DRAWINGS

[0258] Various other features and attendant advantages of the presentinvention will be more fully appreciated as the same becomes betterunderstood when considered in conjunction with the accompanyingdrawings, in which like reference characters designate the same orsimilar parts throughout the several views, and wherein:

[0259] FIG. 1 shows the results from the measurement cell described inExample 4, with the cyclic voltammograms being recorded under theconditions quoted in this example with dilithiumperfluoro-1,2-bis(diethyltrifluorophosphato)ethane as conductive salt.

[0260] The entire disclosure of all applications, patents andpublications, cited above and below and of corresponding GermanApplication No. 10109032.3, filed Feb. 24, 2001 is hereby incorporatedby reference.

[0261] In the foregoing and in the following examples, all temperaturesare set forth uncorrected in degrees Celsius; and unless otherwiseindicated, all parts and percentages are by weight.

[0262] The invention is explained below with relevance to examples.These examples serve merely to explain the invention and do not restrictthe general inventive concept.

EXAMPLES Example 1 Synthesis of dilithiumperfluoro-1,2-bis(diethyltrifluorophosphato)ethane

[0263] 9.50 g of a solvent mixture (ethylene carbonate:dimethylcarbonate:diethylcarbonate=2:2:1 ratio by weight) and 3.50 g (4.9 mmol)of perfluoro-1,2-bis(diethyldifluorophosphorano)ethane were added atroom temperature to 0.44 g (16.9 mmol) of LiF in a PFA vessel under adry gas atmosphere. The reaction mixture was stirred at room temperaturefor three hours until all theperfluoro-1,2-bis(diethyldifluorophosphorano)ethane (base sediment) haddissolved. The excess LiF was filtered off, and the solution(electrolyte), which comprised 3.75 g of dilithiumperfluoro-1,2-bis(diethyltrifluorophosphato)ethane (corresponding to asalt concentration in the electrolyte solution of 28.3% or 0.48 mol/l),was analysed by ¹⁹F and ³¹P NMR spectra. To this end, the spectra weremeasured for clean electrolytes in an FEP tube without dilution withanother solvent using a special method (CD₃COCD₃ film). CCl₃F was usedas external reference in the film. The frequency of 566.22 Hz of 85%H₃PO₄ in water as ³¹P reference in acetone-D₆ was separately determinedexperimentally. Both ¹⁹F and ³¹P NMR spectra were measured using aBruker DRX 500 spectrometer (470.6 MHz for ¹⁹F and 202.5 MHz for ³¹P).

[0264] The ¹⁹F and ³¹P NMR spectra show the formation of differentstereoisomers of the salt dilithiumperfluoro-1,2-bis(diethyltrifluorophosphato)ethane through the reactionof the fluoride ion with the phosphorus atom between perfluoroethylgroups or between perfluoroethyl group and perfluoroethylene bridge inthe starting molecule perfluoro-1,2-bis(diethyldifluorophosphorano)ethane.

[0265] 2 Li⁺[(C₂F₅)₂PF₃(CF₂)₂PF₃(C₂F₅)₂]²⁻

[0266] Isomer A (about 67%)

[0267]¹⁹F NMR: −46.19 dm (2 F, 2 PF); −87.57 dm (4 F, 2 PF₂); −82.28 m(6 F, 2 CF₃);

[0268] −82.42 m (6 F, 2 CF₃); −112.00 dm (4 F, 2 CF₂); −115.13 dm (4 F,2 CF₂); −116.25 dm (4 F, 2 CF₂);

[0269] J¹ _(P,F)=927 Hz; J¹ _(P,F)=922 Hz; J² _(P,F)=105 Hz; J²_(P,F)=74 Hz; J² _(P,F)77 Hz.

[0270]³¹P NMR: −144.7 qm

[0271] Isomer B (about 33 %) ¹⁹F NMR: −43.39 dm (2 F, 2 PF); −87.73 dm(4 F, 2 PF₂); −80.39 m (12 F, 4 CF₃); −110.55 dm (4 F, 2 CF₂); −115.70dm (8 F, 4 CF₂);

[0272] J¹ _(P,F)=860 Hz; J¹ _(P,F)=930 Hz.

[0273]³¹P NMR: −144.8 qm

Example 2 Synthesis of a mixture of Dilithiumperfluoro-1,2-bis(diethyltrifluorophosphato)-ethane and lithiumtris(pentafluoroethyl)trifluorophosphate

[0274] 9.27 g of a solvent mixture (ethylene carbonate: dimethylcarbonate:diethyl carbonate=2:2:1 ratio by weight) and 3.39 g of amixture of perfluoro-1,2-bis(diethyldifluorophosphorano)ethane (about 60mol %) and tris(pentafluoroethyl)difluorophosphorane (about 40 mol %)[this mixture was prepared by electrochemical fluorination of1,2-bis(diethylphosphino)ethane and used further without separation]were added at room temperature to 0.46 g (17.7 mmol) of LiF in a PFAvessel under a dry gas atmosphere. The reaction mixture was stirred atroom temperature for three hours until all the perfluorinated startingmaterial (base sediment) had dissolved. The excess LiF was filtered off,and the solution (electrolyte), which comprised 2.6 g of dilithiumperfluoro-1,2-bis(diethyltrifluorophosphato)ethane (corresponding to asalt concentration in the electrolyte solution of 0.34 mol/l) and 1.02 gof lithium tris(pentafluoroethyl)trifluorophosphate (corresponding to asalt concentration in the electrolyte solution of 0.23 ml/l), wasanalysed by ¹⁹F and ³¹P NMR spectra. The total concentration of the saltin the electrolyte solution was 28.1%. To this end, the spectra weremeasured as described under Example 1 and confirm the presence of thetwo salts in the solution.

[0275] 2 Li⁺[(C₂F₅)₂PF₃(CF₂)₂PF₃(C₂F₅)₂]⁻² (about 60 mol %)

[0276]³¹P NMR: −144.7 qm

[0277] Li⁺[(C₂F₅)₃PF₃]⁻

[0278]³¹P NMR: −150.3 qm

Example 3 Synthesis ofdi(tetraethylammonium)perfluoro-1,2-bis(diethyltrifluorophosphato)ethane

[0279] The synthesis ofdi(tetraethylammonium)perfluoro-1,2-bis(diethyltrifluoroPhosphato)ethanewas carried out analogously to the synthesis described in Example 1,with anhydrous tetraethylammonium fluoride being used instead of LiF.

[0280]¹⁹F and ³¹P NMR analyses show exclusively signals which can beassigned to the anion (see Example 1).

Example 4 Oxidation stability of theperfluoro-1,2-bis(diethyltrifluorophosphato)ethane anion

[0281] In a measurement cell with platinum working electrode, lithiumcounter-electrode and lithium reference electrode, in each case 5 cyclicvoltammograms were recorded one after the other. To this end, thepotential was firstly increased starting from the rest potential at arate of 10 mV/s to 6 V against Li/Li⁺, and then moved back to the restpotential.

[0282] Electrolyte: 0.5 mol/kg_(solvent) (molality) of dilithiumperfluoro-1,2-bis(diethyltrifluorophosphato)ethane in EC/DMC (1:1,ethylene carbonate/-dimethyl carbonate). The oxidation potential wasdetermined as >5 V against Li/Li⁺ (in this respect, see FIG. 1).

[0283] The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples.

[0284] From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

1. A fluoroalkylphosphate salt of formula (I)(M^(a+))_(b)[(C_(n)F_(2n+1-m)H_(m))_(y)PF_(5-y)(CR₁R₂)_(x)PF_(5-y)(C_(n)F_(2n+1-m)H_(m))_(y)]⁽²⁻⁾_((a·b/2))  (I) wherein M^(a+) is a monovalent, divalent or trivalentcation; a is 1, 2 or 3; b is 2 for a=1, b is 2 for a=3, and b is 1 fora=2; and, in each case, subscripts n, m, x and y satisfy the followingrelationships 1≦n≦8, 0≦m≦2 for n=1 or 2, 0≦m≦4 for 3≦n≦8, 1≦x≦12, 0≦y≦2,where R₁ and R₂ are each independently, fluorine, hydrogen, alkyl having1 to 8 carbon atoms, fluoroalkyl having 1 to 8 carbon atoms orperfluoroalkyl having 1 to 8 carbon atoms; and wherein the substituents(C_(n)F_(2n+1-m)H_(m)) are in each case identical or different.
 2. Afluoroalkylphosphate salt according to claim 1, wherein the cationM^(a+) is an alkali metal cation.
 3. A fluoroalkycylphosphate saltaccording to claim 2, wherein cation M^(a+) is a lithium, sodium orpotassium cation.
 4. A fluoroalkylphosphate salt according to claim 3,wherein the cation M^(a+) is a lithium cation.
 5. A fluoroalkylphosphatesalt according to claim 1, wherein the cation M^(a+) is a magnesium oraluminum cation.
 6. A fluoroalkylphosphate salt according to claim 1,wherein the cation M^(a+) is an organic cation
 7. A fluoroalkylphosphatesalt according to claim 6, wherein the cation M^(a+) is a nitrosylcation, a nitryl cation or an organic cation selected from the formulae[N(R⁷)₄]⁺, [P(R⁷)₄]⁺, [P(N(R⁷)₂)₄]⁺ and [C(N(R⁷)₂)₃]⁺, wherein R⁷, ineach case independently, is H, C₁₋₁₀₋ alkyl or A, where one or more Hatoms in the C₁₋₁₀ alkyl chain may each individually be replaced byfluorine, an aromatic radical which optionally contains one or moreheteroatoms, or a cycloalkyl radical which optionally contains one ormore heteroatoms, and/or one or more C atoms in the alkyl chain may beeach individually replaced by a heteroatom, and A is an aromatic orcycloaliphatic radical, in each case optionally containing one or moreheteroatoms.
 8. A fluoroalkylphosphate salt according to claim 7,wherein A is in each case a 5- or 6-membered aromatic radical whichoptionally contains nitrogen, sulfur and/or oxygen atoms, or acycloalkyl radical having 5 or 6 members.
 9. A fluoroalkylphosphate saltaccording to claim 8, wherein A is phenyl or pyridyl.
 10. Afluoroalkylphosphate salt according to claim 6, wherein the M^(a+) is anitrosyl cation, a nitryl cation or an organic cation selected from theformulae [N(R⁷)₄]⁺, [P(R⁷)₄]⁺, [P(N(R⁷)₂)₄]⁺ and [C(N(R⁷)₂)₃]⁺, whereinR⁷ are in each case, independently, are H, C₁₋₁₀₋ alkyl or A, where oneor more H atoms in the C₁₋₁₀₋ alkyl chain may each individually bereplaced by fluorine, a 5- or 6-membered aromatic radical whichoptionally contains one or more heteroatoms selected from N, O and S, ora 5- or 6-numbered cycloalkyl radical which optionally contains one ormore heteroatoms selected from N, O and S, and/or one or more C atoms inthe C₁₋₁₀₋ alkyll chain may be each individually replaced by oxygen, andA is an aromatic or cycloaliphatic radical, in each case optionallycontaining one or more heteroatoms.
 11. A fluoroalkylphosphate saltaccording to claim 1, wherein M^(a+) is a heteroaromatic cation offormulae (II) to (IX)

wherein R¹ to R⁶ are each independently, H, halogen, or a C₁₋₈-alkylradical which is optionally substituted by F, Cl,N(C_(r)F_((2r+1-s))H_(s))₂, O(C_(r)F_((2r+1-s))H_(s)),SO₂(C_(r)F_((2r+1-s))H_(s)) or C_(r)F_((2r+1-s))H_(s), in which 1≦r≦6and 0≦s≦13, and 2r+1-s≦0, or one or more adjacent pairs of R¹ to R⁶ cantogether be a C₁₋₈₋alkylene radical which is optionally substituted byF, Cl, N(C_(r)F_((2r+1-s))H_(s))₂, O(C_(r)F_((2r+1-s))H_(s)),SO₂(C_(r)F_((2r+1-s))H_(s)) or C_(r)F_((2r+1-s))H_(s), in which 1≦r≦6and 0≦s≦13, and 2r+1-s≦0, where each of R¹ to R⁶ cannot be halogens ifthey are bonded directly to nitrogen.
 12. A fluoroalkylphosphate saltsaccording to claim 10, wherein R¹ to R⁶ are each independently H,fluorine, or a C₁₋₈-alkyl radical which is optionally substituted by F,Cl, N(C_(r)F_((2r+1-s))H_(s))₂, O(C_(r)F_((2r+1-s))H_(s)),SO₂(C_(r)F_((2r+1-s))H_(s)) or C_(r)F_((2r+1-s))H_(s), in which 1≦r≦6 or0≦s≦2r+1, and 2r+1-s≦0, and where each of R¹ to R⁶ cannot be fluorine ifthey are bonded directly to nitrogen.
 13. A fluoroalkylphosphate saltaccording to claim 1, wherein 1≦n≦6.
 14. A fluoroalkylphosphate saltaccording to claim 13, wherein 1≦n≦3. 1≦x≦4.
 15. A fluoroalkylphosphatesalt according to claim 1, wherein 1≦x≦8.
 16. A fluoroalkylphosphatesalt according to claim 15, wherein 1≦x≦4.
 17. A fluoroalkylphosphatesalt according to claims 1, wherein m=0.
 18. A fluoroalkylphosphate saltaccording to claim 1, wherein y=2.
 19. A fluoroalkylphosphate saltaccording to claim 1, wherein R₁ and R₂ are each fluorine.
 20. Afluoroalkylphosphate salt according to claim 1, wherein said salt is(Li⁺)₂[(C₂F₅)₂PF₃(CF₂)₂PF₃(C₂F₅)₂]⁽²⁻⁾ or (N(C₂H₅)₄⁺)₂[(C₂F₅)₂PF₃(CF₂)₂PF₃(C₂F₅)₂]⁽²⁻⁾
 21. A process for the preparation ofa fluoroalkylphosphate salt according to claim 1, comprising: reactingat least one fluoro-α,ω-bis[(fluoroalkyl)fluorophosphorano]alkane withat least one fluoride salt of the formula (X) (M^(a+))[F⁻]_(a)  (X)  inwhich (M^(a+)) and a are as defined in claim 1, in solution to obtain afluoroalkylphosphate salt of the formula (I), and said salt isoptionally, purified and/or isolated.
 22. A process according to claim21, wherein said at least onefluoro-α,ω-bis[(fluoroalkyl)fluorophosphorano]alkane is a compound offormula (XI)(C_(n)F_(2n+1-m)H_(m))_(y)PF_(4-y)(CR₁R₂)_(x)PF_(4-y)(C_(n)F_(2n+1-m)H_(m))_(y)  (XI)in which 1≦n≦8, 0≦m≦2 for n=1 or 2, 0≦m≦4 for 3≦n≦8, 1≦x≦12, 0≦y≦2, R₁and R₂ are each, independently, fluorine, hydrogen, alkyl having 1 to 8C atoms, fluoroalkyl having 1 to 8 C atoms or perfluoroalkyl having 1 to8 C atoms, and substituents (C_(n)F_(2n+1-m)H_(m)) are in each caseidentical or different.
 23. A process according to claim 21, wherein thecompound of the formula (X) is employed in an excess of up to 10 fold,based on the amount of fluoro-α,ω-bis[(fluoroalkyl)fluorophosphorano]alkane(s).
 24. A process according to one of claim 21,wherein the reaction with the compound of formula (X) is carried out ata temperature of −35 to +80° C.
 25. A process according to one of claim21, wherein that the solvent employed is ethylene carbonate, propylenecarbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate,ethyl methyl carbonate, methyl propyl carbonate, methyl formate, ethylformate, methyl acetate, ethyl acetate, methyl propionate, ethylpropionate, methyl butyrate, ethyl butyrate, γ-butyrolactone, diethylether, dimethoxyethane, diethoxyethane, dimethylformamide ordimethylacetamide, dimethyl sulfoxide, dimethyl sulfide, diethyl sulfidepropane sulfone, acetonitrile, acrylonitrile, propionitrile, acetone, oran at least partially fluorinated derivative of any of these solvents,or a mixture of at least two of these solvents and/or fluorinatedderivatives of these solvents.
 26. A mixture comprising: a. at least onefluoroalkylphosphate salt according to claim 1, and b. at least onepolymer.
 27. A mixture according to claim 26, comprising 5 to 90% byweight of component a) and 95 to 5% by weight of component b), based onthe sum of components a) and b).
 28. A mixture according to claim 25,wherein component b) is a homopolymer or copolymer of acrylonitrile,vinylidene difluoride, methyl methacrylate, tetrahydrofuran, ethyleneoxide, siloxane, phosphazene or a mixture of at least two of thesehomopolymers and/or copolymers.
 29. A mixture according to claim 28,wherein b) is a homopolymer or copolymer of vinylidene difluoride,acrylonitrile, methyl methacrylate or tetrahydrofuran.
 30. A mixtureaccording to claim 25, wherein said polymer is at least partiallycrosslinked.
 31. A mixture according to claim 25, wherein said itadditionally comprises at least one solvent.
 32. A mixture according toclaim 31, wherein said solvent is ethylene carbonate, propylenecarbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate,ethyl methyl carbonate, methyl propyl carbonate, methyl formate, ethylformate, methyl acetate, ethyl acetate, methyl propionate, ethylpropionate, methyl butyrate, ethyl butyrate, γ-butyrolactone, diethylether, dimethoxyethane, diethoxyethane, dimethylformamide,dimethylacetamide, dimethyl sulfoxide, dimethyl sulfide, diethyl sulfideor propane sulfone, acetonitrile, acrylonitrile, acetone, or an at leastpartially fluorinated derivative of the any of these solvents, or amixture of at least two of these solvents and/or fluorinated derivativesof these solvents.
 33. In an electrolyte, primary battery, secondarybattery, capacitor, super capacitor or galvanic cell, containing atleast one conductive salt, the improvement wherein said salt is a saltaccording to claim 1, optionally in combination with further conductivesalts and/or additives.
 34. An electrolyte according to claim
 33. 35. Anelectrolyte according to claim 34, wherein the concentration of thefluoroalkylphosphate salt is 0.01 to 3 mol/l.
 36. A primary batteryaccording to claim
 33. 37. A secondary battery according to claim 33.38. A capacitor according to claim
 33. 39. A supercapacitor according toclaim
 33. 40. A galvanic cell according to claim 33.